Apparatus for solvent extraction of oil from oil-bearing seeds



Aug. 1, 1950 H. R. STRAIGHT APPARATUS FOR SOLVENT EXTRACTION OF 01:.FROM OIL BEARING SEEDS Filed Feb. 20, 1947 Patented Aug. 1, 1950APPARATUS FOR SOLVENT EXTRACTION OF OIL FROM OIL-BEARING SEEDS Halver-R. Straight, Adel, Iowa Application February 20, 1947, Serial N 0.729,691

This invention relates to a solvent extraction" cation, Serial No.652,148, filed March 5, 1946. l

The apparatus therein disclosed consists of a tower or column having acontainer for solvent, into which flaked soy beans are injected. Theflakes are injected at the top of the tower, and

fall by gravity through the solvent over a series of trays or shelves.As the flakes fall on each succeeding tray, sweep blades sweep theflakes oil of that tray onto the next, so that the flakes require moretime in their downward progress than they would in falling free.

The solvent for extracting oil from the seeds is flowed into the towerat the bottom and drawn off at the top, so that the flakes and solventflow in opposite directions. An overflow pipe is provided adjacent thetop of the tower for withdrawing oil-laden solvent, or miscella, fromthe tower.

An object to be obtained in this type of apparatus is that a constantand steady flow of miscella is attained. On reaching a certain levelmiscella will flow out at a uniform rate, as determined by the pumptaking it away. The inflow of solvent is influenced by the rate at whichbean flakes are injected into the tower; the outflow of miscella in turnis dependent on the speed or capacity at which the miscella pumpoperates. If the flakes are injected into the tower at a uniform rate,the flow of the solvent into the tower will be at a substantiallyuniform rate.

When bean flakes are injected in a manner which is not uniform, but inpulsating lots, the level of the miscella may rise at times to anobjectionable height. To prevent continued inflow of solvent under suchconditions, a float control is provided.

The float is adjusted to maintain the level of solvent or miscella inthe tower above the level of the overflow pipe. The float operates achoke valve for increasing and decreasing the rate of flow of solvent tothe tower.

The float control is encased in a cage on the exterior of the tower. Thecage must have connections above and below the solvent level. Difficultyis encountered in connection with the lower point of communicationbetween the cage and the tower, because as the flakes are passingthrough the tower the solvent liberates oil and fines from the flakes,and these fines work their 2 Claims. (Cl. 23--270.5)

way up into the float cage. This is undesirable, since they tend tochoke the passages through the cage and prevent full operation of thefloat. To overcome this difficulty, I provide the lower communicationbetween the cage and tower immediately below one of the shelves ortrays, above referred to. In each space between adjacent shelves, theflakes and fines tend to drop to the bottom of the space, and the upperregion of the space adjacent the undersurface of the next shelf above iscomparatively free of flakes and fines. Thus the possibility of finesentering into the float cage is reduced to a minimum.

As reference to my co-pending application above referred to will show, aconstriction is formed at the upper part of the tower, through which themiscella must pass. As the miscella passes through this constriction,fines and flour from the flakes fall from the miscella and collect atthe bottom of the constriction, and form a filter suspended by thesurfaces defining the constriction. This filter removes the fines fromthe miscella passing upwardly therethrough, whereby the miscellaemerging from the tower is practically free of any solid particles.However, as time goes on, this crust becomes solid, or too tightlyencrusted for the passage of miscella, and must be disintegrated orreduced in solidity.

To provide for disintegration of this filter or crust, I provide aperforated pipe immediately above the filter, and to disintegrate thefllteror crust, solvent is injected through the perforated pipe, fromwhich solid streams impinge on the crust. This forms a number of holesin the crust and weakens it to such an extent that it falls out of thisposition. A new filter is then built up gradually by the flow ofmiscella through the tower.

Another feature of the present invention is a means for accomplishing asteady downward flow of the flakes at the inlet to the tower orcontainer.

The inlet to the tower through which the flakes are injected is ofreduced capacity, relative to the tower and, under certain conditions,there is a tendency of the flakes to bind and choke the inlet. This istrue particularly if the flakes are gummy; they will not flow readily,but tend to choke the inlet passage.

I have overcome this difficulty by a specifically designed and shapedclearing knife. This knife rotates in the inlet passage and is curved toac-- commodate normal downward flow of the flakes.

impinge on or bear against the flakes. This is essential since it isdesirable not to have any crushing effect on the flakes. However, on thefirst instance of any flakes choking the inlet passage, this clearingknife will clear away the flakes causing the choking condition, andpermit the flakes to fall freely.

With these' and otherobjects in View, my invention consists .in theconstruction, arrangement and combination of the various parts of mydevice whereby the objects contemplated are attained, as hereinaftermore fully set forth, pointed out in the claims and illustrated'in theaccompanying drawings, in which:

Figure 1 is a vertical sectional view through the apparatus employing myinvention;

Figure 2 is a horizontal sectional View taken on line 2-2 of Figure 1;

Figure 3 is a view taken approximately on the line 33 of Figure l, and

Figure 4 is an enlarged detail viewof the construction of the outletpipe.

Referring now in. detail to the drawing, the apparatus includes avertical tower or container 12, preferably of cylindrical cross-section,mounted on a base I4. The top of the tower i2 is closed by a dome 16through which is an inlet M3 for the injection of bean flakes, fromwhich oil is to be removed.

The bean flakes are inserted .in hopper 20 from which a screw conveyor22 forces the flakes through the inlet l8. The screw conveyor 22 isoperated by a conventional motor 24.

Mounted at the top of the tower or container I2 in the interior thereofisa tubular member 2% open at the top and bottom and positioned inregistration with-the inlet lalfor the reception of bean flakes from thescrew conveyor22.

Spaced vertically through the tower ,or container 12 area plurality ofshelves or trays 28,

rigidly mounted on the inner surface of the con tainer.

Each shelf 28. is provided with an opening. therethrough indicated at30, and these openings are positionedon alternately opposite sides ofthe container.

Mounted vertically in the container i2 is a rotatableshaft 32 extendingthe full length of the container and driven by gearing 34, which in turnis driven by the motor 24.

Mounted on the shaft 32 adjacent the top of thetubular member 26 is aleveling sweep. 36 which comprises a plurality of arms terminatingadjacent the wall of the tubular member 26.

Secured to the extremity of one of the arms of the sweep 38 is aclearing knife 33, which extends downwardly and terminates adjacent thelower edge of the tubular member 26. Reference to Figures 2 and 3 willshow that the clearing knife 38 is curved rearwardly and downwardly withrespect to the direction of rotation of the leveling sweep. The clearingknife 38 is positioned with one edge leading, and its flat side adjacentthe wall of the tubular member. The clearing knife may also be curvedlinearly to accommodate the curvature of the tubular member 26, so as tofollow the wall of the tubularmember 25 closely in its rotation.

Mounted on'the shaft 32 above the top shelf 28 is a sweep blade 40,which on rotating'with the shaft 32 sweeps the flakes on the top shelf28 toward the opening 30 therein.

,In each .of the spaces between adjacent shelves 28 is another type ofsweep blade 42 employed for the same purpose as the blade Ml, that is,for

sweeping the flakes on the respective Shelf toward the opening 30therein.

Below the bottom shelf 28 is a third type of sweep blade 44, forsweeping the flakes from the bottom of the container into a chute fromwhich the flakes are carried away by an elevator, which will bedescribed later.

The particular construction of the tubular member 26, the shelves 2%,and the sweep blades 46, 42 and laare of the typeshown and described inmy copending application, Serial No. 652,148, filed March 5, 1946, wherethey are described in detail.

The solvent used for extracting the oil from the seeds is preferablyhexane, although other solvents may be used, if desired. As the solventpasses through the container and extracts oil from bean flakes, themixture of solvent and oil is known as miscella, and reference tosolvent in the specification or claims is intended to include miscellaas well, unless the distinction is specifi-- cally referred to.

The solvent is injected into the apparatus through inlet 48. The inlet48 is in communication with a choke valve es and pipe 52 entering thecontainer 2, at the lower part thereof. Fresh solvent is flowed into thecontainer, filling the container until it reaches a normal levelindicated at 54. At a point near the normal level 54 an outlet pipe 56leads from the container, from which a pump pumps the miscella to anevaporator. The evaporator may be of any conventional type and is forthe purpose of separating from the solvent the oil which has beenremoved from the seed flakes. The outlet pipe 56 is provided with ashield, the construction of which will be described later in connectionwith Figure l.

Mounted on the exterior of the container l2 adjacent the top is a floatcage 5.8 having com munication with the interior of the container atpoints 60 and 62. The upper point 69 is above the level 54, and thelower point 62 is disposed immediately below the top shelf 28 and at theside of the container opposite the opening 30 in that shelf. Solventfrom the container enters into the floatcage from the lower pipe at thepoint 62 and finds its level therein equivalent to the level of thesolvent in the container. .A float 64 is mounted in the float cage58 andin response to the level of the solvent in the float cage operates thechoke valve Fill, in a conventional manner.

An elevator 65 is utilized for carrying the flakes from the containerafter they have passed through it. The elevator 66 comprises a down leg68, and an up leg it, connected by an arcuate portion 52 at the bottomof thecontainer. The elevator 66 includes an enclosing casing which hasopen communication with the chute 46 for the reception of flakestherefrom.

The elevator 66 is operated by an appropriate drive means indicatedgenerally at 14. The flakes from the bottom of the container are carriedby the elevator upwardly and dumped into a wringer l6 where solvent ormiscella is wrung from the flakes. The flakes are then conducted away bya screw conveyor t8 to a drier.

Mounted on the up leg "if! of the elevator is a rinsing apparatus,comprising an inlet channel 89 and an outlet channel 82. This rinsingapparatus is that shown and described in my copending application,Serial No. 685,394, filed July 22, 1946, now abandoned, and need not bedescribed in detail herein. Suffice it to say that the general purposeof this rinsing apparatus is to supply fresh solvent for rinsingresidualoil from the flakes, which are carried up in the elevator 66,The operation of the solvent in the container does not take 100% of theoil out, but some is left in, and the supply of fresh solvent iseffective for extracting an additional amount of oil fro theflakes.

The solvent from the rinsing apparatus is not fully laden with oil andaccordingly it can be reused in the container for removing additionaloil from the flakes. An outlet pipe 84 leads from the bottom of thedischarge channel 82, and communicates alternately, as desired, withinlet 52 in the bottom of the casing, or to the down leg 68 of theelevator, as indicated at 86. By injecting solvent into the down leg 68of the elevator, it again finds its way into the container through thechute 46.

It will be noted that the tubular member 26 forms a constricted spacebetween itself and the wall of the container l2. At the bottom of thisconstriction solid particles from the flakes form a filter or crust 88,as explained in my co-pending application, Serial No. 652,148, referredto above. A circular perforated pipe 90 is secured to the wall of thecontainer just above the point where the filter forms. The perforationsin the pipe 9i! extend downwardly or at a slight angle from the lowersurface. An inlet 92 communicates with the pipe 90 for flowing solventinto the perforated pipe for directing solid streams of solvent into thefilter 88.

The inner 'end of the outlet pipe 56 is provided with an elbow, as seenin Figure 4, and a nipple 96 extending upwardly. A speciallyformedfitting 98 is placed on the nipple 9E. The fitting 9B is formedwith a tubular portion Hi0 and a funnel portion M2 opening upwardly. Theinterior of the tubular portion I00 is formed with a tapered bead I04for supporting the fitting 98 on the nipple Q6, and baffling themiscella into the nipple.

A cone-shaped shield Hi6 is positioned in spaced relation over thefunnel portion H32 and secured thereto as by brackets I08. Dependingfrom the marginal edge of the shield IE6 is a skirt HE! formed of screenor mesh material. The skirt H0 extends below the upper marginal edge ofthe funnel portion I02. The assembly is placed so that the uppermarginal edge of the portion I02 is positioned below the normal level ofthe miscella.

Operation In the ideal operation of the device, crushed seed flakes aredelivered through the inlet I8 at a constant rate, and solvent is flowedinto the inlet 52 at a constant rate. When both of these rates of floware constant, the removal of oil from the seed flakes is the mosteflicient.

In the best operation of the device, the column or container i2 is keptsubstantially full of seed flakes, which includes the tubular member 26full to the top. When the tubular member 26 is full of flakes, theleveling sweep 35 rotates and levels the flakes across the whole area ofthe tubular member 26.

If the seed flakes are not in the best condition, for example, if theyshould be slightly gummy, they tend to arch across between the shaft 32and the inner surface of the tubular member 26. For this reason theclearing knife 38 is provided on the leveling sweep 36. In normaloperation of the apparatus, the flakes have a more or less uniform rateof fall. The rearward curvature of the clearing knife 38 is equal to thecircumferential distance traveled by the leveling sweep 36 in the timethat the flakes fall the vertical length of the blade. As long as thenormal rate of fall of flakes prevails, the clearingknife 36 produces noeffect, but only follows the flakes in their path of fall. If any of theflakes should begin to arch across the tubular member 26, and therebychoke the tubular member, the clearing knife 38 will clear those flakesas quickly as they begin to choke.

The flakes substantially fill the space between the top shelf 28 and thelower edge of the tubular memberZB. The sweep arm 40 forces the flakestoward the opening 3|] in that shelf.

In the spaces between adjacent shelves 28, the flakes forma slopeapproximately as indicated immediately below the top shelf 28. The sweepblades 42 gradually and successively sweep the flakes toward the opening30 in successive shelves. Immediately below each shelf on the sidethereof opposite its opening 30, is a space above the lower end of theslope of flakes, in which there is virtually clear solvent or miscella,having no solid particles. At such a point, i. e., immediately below thetop shelf, the inlet 62 of the float cage communicates with the interiorof the container l2. The solvent enters at this point to the 'fioat cageand since it is clear of solid particles, there is small likelihood ofsolid particles choking the passages through the float cage.

If a sudden rush of flakes is injected into the tower, the miscellarises above the normal level. Since the miscella is carried off by apump at a constant rate, it is of course necessary to limit the inflowof solvent under such circumstances. The float 64 on rising with therising level chokes the valve 50 and reduces the inflow of solvent.

The filter 88 is formed as a result of continued action over quite aperiod of time. Particles of seed flakes bridge across the lower end ofthe constriction between the tubular member 26, and the shell of thecontainer l2. During this process the solvent on passing upwardlythrough the filter leaves small particles of flakes which were carriedwith it, known as fines or flour, and emerges as substantially clearliquid. The flakes emerging from the lower end of the tubular member 26work outwardly along the under-surface of the filter, as indicated bythe arrows 94. The tendency of this brushing of flakes is to keep thefilter 88 somewhat clear and prevent it from becoming solid.Nevertheless, the filter eventually does become solid and after aprolonged length of time would prevent a sufficiently free passage ofliquid therethrough. The perforated pipe 90 therefore is brought intoplay under such conditions. Solvent is injected through the inlet 92into the perforated pipe 90 and concentrated streams of solvent emergefrom the downwardly directed openings in the pipe and penetrate thefilter. This forms holes in the filter, which breaks up the filter andpermits it to drop, and a new filter is formed over a period of time, asexplained above.

It will be noted that in disintegrating the filter, the flow of solventis reversed through a portion of the container. When the flow of solventis thus temporarily reversed at this point, inflow of solvent at theinlet 52 may be cut off or reduced.

The shield assembly on the outlet pipe 56 prevents foreign matter fromentering the outlet pipe 56, and consequent possible choking of thepipe. Any foreign material in the tower tends to form a film on thesurface of the miscella. Since the screen skirt H0 extends below theupper edge of the portion I02, such film of foreign matter is preventedfrom entering the outlet pipe. The outer surface of the screen skirt Hcan be cleared from'foreign matter at intervals as desired.

The normal level of the miscella in the tower may remain above theoutlet pipe, because the rate of outflow is determined by the speed ofoperation of the miscella pump'referred to above.

While I have shown a particular embodiment of my invention, it will beunderstood of course that I do not wish to be limited thereto, sincemany modifications may be made, and I therefore contemplate by theclaims appended hereto to cover any such modifications or'substitutionsof mechanical equivalents as fall within the true spirit and scope of myinvention.

I claim:

1. In a solvent extraction apparatus, a containe'r, means for providingflow of solvent upwardly through said container including an outletadjacent' the top of the container, a tubular member at the top of thecontainer terminating at a point below said outlet, means for supplyingseed flakes through said tubular memher into the container, a levellingsweep rotatably mounted in the upper part of said tubular member, aclearing knifesecured to the periphery of said levelling sweep andextending downwardly to substantially the lower extremity of saidtubular 'inember, said tubular member forming a constriction with thecontainer whereby a filter of seed particles is formed in saidconstriction by the flow of solvent therethrough, means in saidconstriction above and adjacent to the bottom thereof for directing astream of solvent 8 I downwardly and float control means for controllingthe fiow of solvent through the container, said float control meansbeing secured to the exterior of the container and having communicationwith the interior of the container above and below said filterrespectively.

2. In a solvent extraction apparatus, a container, means for causingupward flow of solvent through the container, a tubular member forreceiving oil-bearing flakes supported in the upper part of thecontainer, a levelling sweep rotatably mounted in the upper part of saidtubular member, and extending to adjacent the periphery of said tubularmember, and a clearing knife secured to the periphery of said levellingsweep and extending downwardly to substantially the lower extremity ofsaid tubular member, the lower end of said clearing knife being curvedrearwardly with respect'to the direction of rotation of said levellingsweep.

HALVER R. STRAIGHT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,158,782 Bonotto May 16, 19392,187,890 Pattee Jan. 23, 1940 2,276,298 Frazier Mar. 17, 1942 2,282,265Swallen May 5, 1942 2,299,426 Rosebough Oct. 20, 1942

1. IN A SOLVENT EXTRACTION APPARATUS, A CONTAINER, MEANS FOR PROVIDINGFLOW OF SOLVENT UPWARDLY THROUGH SAID CONTAINER INCLUDING AN OUTLETADJACENT THE TOP OF THE CONTAINER, A TUBULAR MEMBER AT THE TOP OF THECONTAINER TERMINATING AT A POINT BELOW SAID OUTLET, MEANS FOR SUPPLYINGSEED FLAKES THROUGH SAID TUBULAR MEMBER INTO THE CONTAINER, A LEVELLINGSWEEP ROTATABLY MOUNTED IN THE UPPER PART OF SAID TUBULAR MEMBER, ACLEARING KNIFE SECURED TO THE PERIPHERY OF SAID LEVELLING SWWEEP ANDEXTNEDING DOWNWARDLY TO SUBSTANTIALLY THE LOWER EXTREMITY OF SAIDTUBULAR MEMBER, SAID TUBULAR MEMBER FORMING A CONSTRICTION WITH THECONTAINER WHEREBY A FILTER OF SEED PARTICLES IS FORMED IN SAIDCONSTRICTIN BY THE FLOW OF SOLVENT THERETHROUGH, MEANS IN SAIDCONSTRICTION ABOVE AND ADJACENT TO THE BOTTOM THEREOF FOR DIRECTING ASTREAM OF SOLVENT DOWNWARDLY AND FLOAT CONTROL MEANS FOR CONTROLLING THEFLOW OF SOLVENT THROUGH THE CONTAINER, SAID FLOAT CONTROL MEANS BEINGSECURED TO THE EXTERIOR OF THE CONTAINER AND HAVING COMMUNICATION WITHTHE INTERIOR OF THE CONTAINER ABOVE AND BELOW SAID FILTER RESPECTIVELY.